摘要:
A substantially surface-deactivated catalyst composition that is stable at least to 300° C. The catalyst includes a zeolite catalyst (e.g., ZSM-22, ZSM-23, or ZSM-57) having active internal Brönsted acid sites and a surface-deactivating amount of a rare earth or yttrium oxide (e.g., chosen from lanthanum oxide or lanthanides oxide). This to catalyst is preferably used in a process for producing a higher olefin by oligomerizing a light olefin, wherein the process includes contacting a light olefin under oligomerization conditions with the substantially surface-deactivated catalyst composition.
摘要:
A substantially surface-deactivated catalyst composition that is stable at least to 300° C. The catalyst includes a zeolite catalyst (e.g., ZSM-22, ZSM-23, or ZSM-57) having active internal Brönsted acid sites and a surface-deactivating amount of a rare earth or yttrium oxide (e.g., chosen from lanthanum oxide or lanthanides oxide). This catalyst is preferably used in a process for producing a higher olefin by oligomerizing a light olefin, wherein the process includes contacting a light olefin under oligomerization conditions with the substantially surface-deactivated catalyst composition.
摘要:
A method for reduction of NOx in a lean gaseous stream includes passing the gaseous stream at a temperature within the NOx sorbing temperature range through a catalyzed trap member having an oxidation catalyst intimately combined with a sorbent material. The sorbed NOx is periodically removed by introducing a combustible component into the gaseous stream and oxidizing it on the trap member to thermally desorb the NOx. The amount of combustible component introduced is limited to maintain the gaseous stream bulk composition lean and to avoid increasing the bulk temperature of the gaseous stream to a temperature which is too high for effective lean NOx abatement treatment. A suitable NOx abatement catalyst is used to reduce the desorbed NOx. Sorbing (trapping) and desorbing periods are alternated, usually in response to the temperature of the gaseous stream, and an apparatus to carry out the process is provided.
摘要:
A NO.sub.x abatement composition comprises a NO.sub.x abatement catalyst and a NO.sub.x sorbent material which are dispersed in proximity to, but segregated from, each other on a common refractory carrier member (10). The NO.sub.x sorbent material comprises a basic oxygenated metal compound and optionally further comprises ceria. The NO.sub.x abatement catalyst contains a catalytic metal component including a platinum metal catalytic component. The catalytic metal component is segregated from the NO.sub.x sorbent material, which may be one or more of metal oxides, metal carbonates, metal hydroxides and mixed metal oxides. At least the catalytic metal component and the NO.sub.x sorbent material must be on, or comprise separate, particles; the particles may either be admixed or may be disposed in separate layers (20a, 20b) on the carrier member (10). A NO.sub.x abatement method employs the composition and includes periodically adjusting the gas being treated between lean and stoichiometric/rich operating cycles.
摘要:
A catalyst member for use in processes for the catalytic combustion of gaseous carbonaceous fuels is made from a stabilized carrier having a plurality of gas flow passages extending therethrough defined by channel walls and a catalyst material disposed on the channel walls, wherein the carrier is stabilized against interaction with the catalyst material. The stabilized carrier may be prepared from a monolith comprising silica, magnesia and alumina that has a coating of alumina on the channel walls and by subjecting the coated monolith to stabilizing conditions. The stabilizing conditions may include exposure to high temperature steam.
摘要:
Catalytic partial oxidation is effected in the presence of a supported, Group VIII metal catalyst by reacting a light hydrocarbon with an oxygen containing gas, the catalyst support being in a preferred size range.
摘要:
A method for reducing gaseous nitrogen oxides present in a gas stream by reaction with a reductant species is practiced by flowing the gas stream under lean NO.sub.X -reducing conditions in contact with a catalytic material containing a catalytically effective amount of a catalytic species, e.g., a platinum group metal, and a reductant storage material, e.g., a zeolite, effective for storing reductant species for reaction with NO.sub.X, and providing an intermittent supply of the reductant to the gas stream. The catalytic material may be prepared in any manner, but one method is to incorporate a catalytically effective amount of the platinum into a template-bearing molecular sieve material, preferably ZSM-5 zeolite, to hinder the platinum from being incorporated into the pores of the molecular sieve material, and then calcining the molecular sieve material, whereby the template is removed from the molecular sieve material after the platinum is incorporated therein. Another method is to add a blocking agent to the molecular sieve material, then incorporate the platinum therein, and then calcine the material to remove the blocking agent. The catalytic material may contain less than about two percent by weight of zeolite plus platinum, e.g., less than about 0.5%, or from about 0.025% to 0.1% or 0.2% platinum.
摘要:
A combustor for supporting the catalytic combustion of gaseous carbonaceous fuel contains a catalyst zone in which is disposed a catalyst body comprising at least one catalyst member, a separator zone comprising a separator body and a downstream zone where homogeneous combustion occurs. The catalyst member contains a carrier and a catalyst material deposited thereon. The catalyst body may, optionally, contain additional catalyst members downstream of the at least one catalyst member. The separator body contains a carrier-type monolith containing ceramic fibers in a matrix. One of the optional additional catalyst members may also contain such a monolith on which the catalyst composition is disposed.
摘要:
A catalyst bed (30) for a combustor (18) for supporting the catalytic combustion of a gaseous air/fuel (e.g., methane or natural gas) combustion mixture contains an igniter catalyst member (1) upstream of a promoter catalyst member (2). The catalyst members each comprise carrier monoliths, the igniter catalyst member (1) having an igniter catalyst material deposited thereon and the promoter catalyst member (2) having a promoter catalyst material deposited thereon. The igniter catalyst material is distinguished from the promoter catalyst material in one or more of the following ways: the igniter catalyst material may have (a) a higher catalytic activity for combustion of the air/fuel mixture, (b) a lower catalyst deactivation temperature than the promoter catalyst material, and/or (c) the promoter catalyst regeneration temperature range brackets the upper limit of the regeneration temperature range of the igniter catalyst.
摘要:
A method for reducing gaseous nitrogen oxides present in a gas stream by reaction with a reductant species is practiced by flowing the gas stream under lean NO.sub.X -reducing conditions in contact with a catalytic material containing a catalytically effective amount of a catalytic species, e.g., a platinum group metal, and a reductant storage material, e.g., a zeolite, effective for storing reductant species for reaction with NO.sub.X, and providing an intermittent supply of the reductant to the gas stream. The catalytic material may be prepared in any manner, but one method is to incorporate a catalytically effective amount of the platinum into a template-bearing molecular sieve material, preferably ZSM-5, to hinder the platinum from being incorporated into the pores of the molecular sieve material, and then calcining the molecular sieve material, whereby the template is removed from the molecular sieve material after the platinum is incorporated therein. Another method is to add a blocking agent to the molecular sieve material, then incorporate the platinum therein, and then calcine the material to remove the blocking agent. The catalytic material may contain less than about two percent by weight of zeolite plus platinum, e.g., less than about 0.5%, or from about 0.025% to 0.1% or 0.2% platinum.